Steady‐state and dynamic rheology of poly(1‐olefin) melts

Wang, Jeou-shyong; Knox, Jack R.; Porter, Roger S.

doi:10.1002/pol.1978.180161001

Cited by 17 publications

(2 citation statements)

References 21 publications

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“…This is in accordance with Wang et al [50], who found a significant decrease of & 0 for longer poly-!-olefins in comparison to PE. However, it remains puzzling why the sample F26F [51] has almost the same weight comonomer content w c (having fewer but longer butacosene (C24) side chains) yet obeys the & 0 -M w -correlation of HDPE [38].…”

Section: Rheology 331 Zero Shear-rate Viscosity !supporting

confidence: 82%

Evidence of intra-chain phase separation in molten short-chain branched polyethylene

Stadler¹

2011

Express Polym. Lett.

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Abstract. Intramolecular phase separation is usually associated with block-copolymers, but the same phenomenon is also obtainable by random-copolymers. In this article, evidence of intramolecular phase separation is reported for a linear octadecene-ethene copolymer, which shows an evolving 'yield point' at a long time and low frequency. This is attributed to a partial phase separation of the long short-chain branches. In creep recovery, this behavior is evident as increasing elastic steady-state creep recovery compliance J e 0 . In contrast to 'normal' block-copolymers, this special polymer has an increase in phase separation with temperature, which is caused by the chemical composition and the short chain segments in the side chain domain, leading to a high surface fraction. Vol.5, No.4 (2011) 327-341 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2011 * Corresponding author, e-mail: fjstadler@jbnu.ac.kr © BME-PT length in their paper, as it cannot be determined due to the synthesis method. Such block-copolymers are usually thermorheologically complex [9,14,15]. The group of Bates [9,10], for example, found that below the order-disorder transition temperature, i.e., in the ordered state, the sample behaves like a gel and thermorheologically simple, while in the disordered state, a clear thermorheological complexity is found. The higher the temperature, the less pronounced the long-term relaxation process and, thus, the more similar is the data to a single-phase polymer melt. Recently, it was also proven that pure ethylene-/!-olefin copolymers with very long comonomers (C26) can be phase separating in the solid state, if their comonomer content is sufficiently high [16]. This effect is different from the previous cases, because it only involves one type of chain and, furthermore, occurs on random copolymers. Hence, it is an effect that occurs only on a short length scale, as shown by the fact that the length of the comonomers used were 18 and 26 carbons. Thus, the second phase has to encompass only the maximum of 24 terminal carbons; realistically, 16-20 carbons. This effect had a small trace in X-ray diffraction, which points to a weak side chain crystallization [17,18]. However, it was shown that the samples showing this phase behavior in the solid state [16] did not show it in the melt state, as the samples behaved like normal linear low density polyethylenes (LLDPEs), being only special because of their higher flow activation energy E a , which is the consequence of the side-chain content s c of the comonomer [19,20]. Phase separation in the melt is usually visible by traces of the interfacial tension [21] and different temperature dependencies of the individual blend components and the interfacial processes [22,23]. Hence, if other techniques don't show any trace, e.g., because of too low differences in the electron density in X-ray scattering, rheological behavior can provide a valuable aid to the characterization of phase separation. Recently, molecular dynamics studies revea...

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Section: Rheology 331 Zero Shear-rate Viscosity !supporting

confidence: 82%

Evidence of intra-chain phase separation in molten short-chain branched polyethylene

Stadler¹

2011

Express Polym. Lett.

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“…The data are summarized in Figure 3. We used the Cox–Merz rule23 [η*(ω) = η(γ˙)], which was found to be valid by earlier investigators24–31 for polyethylene and its copolymers, to obtain the steady shear viscosity. η 0 gives information about the zero shear viscosity.…”

Section: Methodsmentioning

confidence: 99%

Structure development in melt spinning of poly(ethylene‐co‐octene) filaments with various comonomer contents

Shan

White

2004

J of Applied Polymer Sci

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An experimental study of the spinnability and the variation in crystallinity and orientation of melt spinning of poly(ethylene-co-octene) with different contents of comonomers was carried out. The spinning behavior of these polymers was investigated under different drawdown ratios and temperatures and correlated to spinline stress. The melt-spun filaments were characterized by wideangle X-ray diffraction birefringence, and differential scanning calorimetry. S-1 is a high-density polyethylene and S-2, S-3, and S-4 have 16, 22, and 38 wt % octene. An orthorhombic unit cell was found in all four polymers, but a dominant hexagonal structure (perhaps mesophase) was found for the highest octene level (S-4). The orientation factors for the a-, b-, and c-axis of the orthorhombic crystal structure and a-axis of the hexagonal phase were then calculated. The crystalline orientation behavior of the lower octene copolymers (S-1, S-2, and S-3) are similar and can be represented as a "rownucleated" structure. However, the orientation behavior of S-4 was different. The uniaxial mechanical properties were also measured. The Young's modulus and tensile strength generally increased with birefringence for all polymers. With increasing content of octene, the Young's modulus showed a decrease from semicrystalline thermoplastic toward an elastomer.

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Butene Polymers

Chatterjee¹

2008

Encyclopedia of Polymer Science and Technology

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Polybutylene (PB) refers to a series of commercial semicrystalline resins derived from high molecular weight, predominantly isotactic poly(1‐butene) homopolymer or copolymer. 1‐Butene is manufacture by the catalytic oligomerization of ethylene. It can also be manufactured from mixed butylenes streams: acid extraction, the Sorbutene process, and the methyl tert ‐butyl ether process. Isotactic poly (1‐butene) is manufactured by a stereospecific Zeigler‐Natta polymerization. In melt processing of commercial PB resins, two crystal forms are encountered. PB pipe can be fabricated by extrusion, PB film is produced by a blown film process. Other processing systems are also discussed. The most important commercial outlet for PB resins is in pipe with applications that include cold‐water service and cold‐ and hot‐ water plumbing. Some other pipe applications include well piping, heat‐pump piping, and fire‐sprinkler piping. The advantages of PB in pipe applications include flexibility, toughness, resistance to creep, environmental stress cracking, wet abrasion, and chemicals. PB can also be used in seals on containers and packages since it has the ability to peel with controllable force. Data are also given on specifications and analytical methods. 1‐Butene is flammable. It is not toxic at moderate concentrations, higher concentrations cause an anesthetic effect,

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Steady‐state and dynamic rheology of poly(1‐olefin) melts

Cited by 17 publications

References 21 publications

Evidence of intra-chain phase separation in molten short-chain branched polyethylene

Evidence of intra-chain phase separation in molten short-chain branched polyethylene

Structure development in melt spinning of poly(ethylene‐co‐octene) filaments with various comonomer contents

Butene Polymers

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